Corroded support beam for freshwater tank

[Thorick]

Hi AGAIN,
While looking for additional water shutoff valves to drain my freshwater tank, I discovered these rusted and deteriorating support beams under it. Has anybody encountered this? Being a complete newbie and an idiot for not seeing this, I'm thinking the freshwater tank has to come out to allow replacement of the support beams. I certainly can't put the weight of even a half full tank on these without fear that the tank will fall thru. 1st 1 is full beam, 2nd is left side, the next 2 are right side. Thank you for your thoughts,

[Bob Denman]

My Riffin Wayfarer just had a recall for that same problem.
After all: It's rude to drop your tank in traffic...